Forming of the snap heads of rivets



March 16, 1965 s. BODMER 3,173,281

FORMING OF THE SNAP HEADS OF RIVETS Filed Dec. 3, 1962 INVENTOE bzzfm'eci fiodmerf) 7' 701 NE Y5 United States Patent Ofi ice 3,173,281 Patented Mar. 16, 1965 3,173,281 FORMING OF THE SNAP HEADS F RIVETS Gottfried Bodrner, 21 Florastrasse, Kusnacht, Zurich, Switzerland Filed Dec. 3, 1962, Ser. No. 241,948 3 Claims. (Cl. 7267) The present invention relates to the forming of the snap heads of rivets.

Beside the known method of riveting by impact by means of riveting hammers, which causes a loud noise, pressure riveting by mechanical, pneumatic or hydraulic riveting presses has been successfully introduced, since the same operates almost noiselessly. When pressing the rivets however a strong deformation of the whole rivet shank occurs, which may lead to difiiculties when setting the rivets into delicate rivet carriers. In order to obviate these disadvantages the rolling of rivets has already become known. In this process the snap heads of the rivets are pressed by means of a rotary riveting tool, which carries two hard metal rollers inclined to one another. The rolling riveting process excels likewise by a very low noise level, but has the disadvantage, that the riveting tools provided with rollers are comparatively expensive. Moreover these tools occupy rather much space around the snap heads to be formed, so that the rolling riveting process cannot be applied when the rivets have to be set for example along a wall or into recesses or the like.

The present invention has the objects of providing a riveting device, which is free from the disadvantages, inherent to the rolling riveting method, and nevertheless offers the advantage of a quiet manner of operation.

With these and other objects in view which will become apparent later from this specification and the accompanying drawing I provide a device for the formation of snap heads on rivets by riveting that performs the simultaneous steps of applying axial pressure and a wobbling motion to a rotationally stationary die in contact with the portion of the rivet to be formed into the snap head of a shape complementary to said snap head.

The riveting devices for the forming of snap heads on rivets comprises in combination: a rotatable and axially shiftable tool holder having a bearing bore extending at an acute angle to the longitudinal axis of said tool holder, a riveting tool inserted in said bore and having a concave end face projecting from said bore, the point of intersection of the longitudinal axis of said tool holder with the axis of said bore lying substantially on said concave end face, and detent means preventing the rotation of said tool relative to the rivet portion to be formed into the snap head.

The said acute angle amounts preferably to between 2 and These and other features of my said invention will be clearly understood from the following description of a preferred embodiment thereof given by way of example with reference to the accompanying drawing, the single figure of which shows in sectional side elevation a tool holder inserted into the rotating spindle of a riveting machine with the riveting tool inserted, at the beginning of the formation of a snap head on a rivet.

On a spindle 1 of a riveting machine, such as usually employed for rolling riveting, which accordingly 1s rotatable and axially slidable, a tool holder 2 is screwed fast. The same contains a bearing bore 3 for a riveting tool 4, a so called snap die of conventional type, which at its lower end face projecting from the tool holder 2 has a hardened concave face 5, which serves for the forming of the snap head 7 (indicated in dotted lines) of the rivet 6, the swage head of which rests in the usual manner on a counter support 8. The snap head die 4 is mounted rotatably in the bore 3 and rests on a steel ball 9. It is detained by a spring-loaded ball 10, which engages into a groove 11.

The axis of the bore 3 and accordingly of the snap head die 4 is inclined relative to the axis of the tool holder 2 an acute angle a, the two axes intersecting at a point, which lies approximately on the concave end face 5. The angle 0: is selected substantially between 2 and 10, depending on the material and size of the rivet. In the snap head die 4 there is moreover fixed a rod 12, which abuts a stationary stop 13 and prevents the snap head die from taking part in the rotation of the tool holder 2.

For the forming of the snap head 7 the spindle 1 is forced downward, and at the same time is set in rotation. The snap head die 4 describes a wobbling movement about the axis of the tool holder 2 and thereby rolls on the snap head of the rivet which is being formed. The snap head thereby receives an extraordinarily smooth surface. It has been found, that the pressure on the die required for the formation of the snap head amounts to V only of the pressure required for the usual pressure riveting process. In contrast to the pressure riveting process the rivet shank is accordingly not substantially deformed.

The snap head die 4 could alternatively be shaped conically or cylindrically towards the end face, whereby it is made possible to carry out riveting operations also along walls and in recesses, i.e. at places, which were not accessible to rolling riveting tools.

While I have described herein and illustrated in the accompanying drawings what may be considered a typical and particularly useful embodiment of my said invention, I wish it to be understood that I do not limit myself to the particular details and dimensions described and illustrated; for obvious modifications will occur to a person skilled in the art.

What I claim as my invention and desire to secure by Letters Patent is:

1. A machine for upsetting rivet shanks to form the snap head of a rivet comprising a snap head die having an end adapted to engage the rivet and form the snap head, a die holder mounted for axial and rotational movement, means mounting the snap head die in said die holder for axial movement therewith and Wobbling movement and means for preventing rotational movement of the snap head die.

2. The invention as defined in claim 1 in which the die holder has an axis about which it revolves, the snap head die is elongate and has an axis, the axis of the snap head die is at an angle to the axis of the die holder with the point of intersection of the axes being substantially at the end of the snap head die adapted to engage the rivet and the angle between the two axes is between 2 and 10 degrees.

3. The invention as defined in claim 1 in which the last-named means includes the snap head die having a member secured thereto to extend therefrom, the machine includes a stationary portion and the member engages the stationary portion to prevent rotation of the snap head die.

References Cited by the Examiner UNITED STATES PATENTS 740,492 10/03 Veeder 8259 4 1,359,625 11/20 Slick 78-53 2,568,338 9/51 Irmischer 78-53 FOREIGN PATENTS 122,039 6/48 Sweden.

WILLIAM J. STEPHENSON, Primary Examiner. 

1. A MACHINE FOR UPSETTING RIVET SHANKS TO FORM THE SNAP HEAD OF A RIVET COMPRISING A SNAP HEAD DIE HAVING AN END ADAPTED TO ENGAGE THE RIVET AND FORM THE SNAP HEAD, A DIE HOLDER MOUNTED FOR AXIAL AND ROTATIONAL MOVEMENT, MEANS MOUNTING THE SNAP HEAD DIE IN SAID DIE HOLDER FOR AXIAL MOVEMENT THEREWITH AND WOBBLING MOVEMENT AND MEANS FOR PREVENTING ROTATIONAL MOVEMENT OF THE SNAP HEAD DIE. 